1. Technical Field
The embodiments herein generally relate to microelectronic systems, and more particularly to microelectromechanical systems (MEMS) and MEMS inductor technology.
2. Description of the Related Art
MEMS devices are micro-dimensioned machines manufactured by typical integrated circuit (IC) fabrication techniques. The relatively small size of MEMS devices allows for the production of high speed, low power, and high reliability mechanisms. The fabrication techniques also allow for low cost mass production. MEMS devices typically include both electrical and mechanical components, but may also contain optical, chemical, and biomedical elements. Typically, an inductor is configured as a coil comprising conducting material. For example, copper wire may be wrapped around a ferromagnetic core. Such a core typically has a sufficiently high permeability to confine the magnetic field closely to the inductor, which increases the inductance of the device.
Miniaturization of radio frequency (RF) circuits has generally been limited to a degree by the lack of high performance on-chip inductors. The miniaturization thus far of RF circuits has been exploited by the cellular phone and wireless products markets. Military radios and radar systems also benefit from the further miniaturization of RF circuits. Inductors are found in RF matching networks and voltage controlled oscillators; critical components of RF front ends for transceivers and receivers. In some applications, the inductor may need to be tunable; i.e., the inductance of the inductor capable of being selectively modified.
Tunable RF MEMS inductors are an enabling technology for reconfigurable RF circuits. Reconfigurable RF circuits have received a great deal of attention in recent years and would, for example, enable filter bandwidths to be significantly manipulated as system requirements dictate. In addition, inductors in series or in parallel with filter elements also increase filter bandwidth. At present, integrated inductors, in silicon technologies, have produced inductor Q values of less than five. Moreover, MEMS inductors have shown inductor Q values an order of magnitude greater than this. While the industry has its choice of several designs of inductors to select when utilizing them for incorporation into an electromagnetic device, there remains a need for a novel piezoelectric MEMS inductor device which is capable of being tunable, and which can be incorporated in different types of electrical circuits.